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      1 /*
      2  * Copyright (c) 2015 Eugene Syromyatnikov <evgsyr (at) gmail.com>
      3  * Copyright (c) 2015 Dmitry V. Levin <ldv (at) altlinux.org>
      4  * All rights reserved.
      5  *
      6  * Redistribution and use in source and binary forms, with or without
      7  * modification, are permitted provided that the following conditions
      8  * are met:
      9  * 1. Redistributions of source code must retain the above copyright
     10  *    notice, this list of conditions and the following disclaimer.
     11  * 2. Redistributions in binary form must reproduce the above copyright
     12  *    notice, this list of conditions and the following disclaimer in the
     13  *    documentation and/or other materials provided with the distribution.
     14  * 3. The name of the author may not be used to endorse or promote products
     15  *    derived from this software without specific prior written permission.
     16  *
     17  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
     18  * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
     19  * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
     20  * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
     21  * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
     22  * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
     23  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
     24  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
     25  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
     26  * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
     27  */
     28 
     29 /**
     30  * @file
     31  * This test burns some CPU cycles in user space and kernel space in order to
     32  * get some non-zero values returned by times(2).
     33  */
     34 
     35 #ifdef HAVE_CONFIG_H
     36 # include "config.h"
     37 #endif
     38 
     39 #include <sched.h>
     40 #include <stdio.h>
     41 #include <time.h>
     42 #include <unistd.h>
     43 
     44 #include <sys/syscall.h>
     45 #include <sys/times.h>
     46 #include <sys/wait.h>
     47 
     48 enum {
     49 	NUM_USER_ITERS = 1000000,
     50 	PARENT_CPUTIME_LIMIT_NSEC = 200000000,
     51 	CHILD_CPUTIME_LIMIT_NSEC = 300000000
     52 };
     53 
     54 int
     55 main (void)
     56 {
     57 	struct timespec ts;
     58 	volatile int dummy;
     59 	int i;
     60 
     61 	pid_t pid = fork();
     62 
     63 	if (pid < 0)
     64 		return 77;
     65 
     66 	const long cputime_limit =
     67 		pid ? PARENT_CPUTIME_LIMIT_NSEC : CHILD_CPUTIME_LIMIT_NSEC;
     68 
     69 	/* Enjoying my user time */
     70 	while (clock_gettime(CLOCK_PROCESS_CPUTIME_ID, &ts) == 0) {
     71 		if (ts.tv_sec || ts.tv_nsec >= cputime_limit)
     72 			break;
     73 
     74 		for (i = 0; i < NUM_USER_ITERS; ++i)
     75 			++dummy;
     76 	}
     77 
     78 	/* Enjoying my system time */
     79 	while (clock_gettime(CLOCK_PROCESS_CPUTIME_ID, &ts) == 0) {
     80 		if (ts.tv_sec || ts.tv_nsec >= cputime_limit * 2)
     81 			break;
     82 
     83 		sched_yield();
     84 	}
     85 
     86 	if (pid == 0) {
     87 		return 0;
     88 	} else {
     89 		wait(NULL);
     90 	}
     91 
     92 	struct tms tbuf;
     93 	unsigned long long llres;
     94 
     95 	/*
     96 	 * On systems where user's and kernel's long types are the same,
     97 	 * prefer direct times syscall over libc's times function because
     98 	 * the latter is more prone to return value truncation.
     99 	 */
    100 #undef USE_LIBC_SYSCALL
    101 #if defined __NR_times && \
    102    !defined(LINUX_MIPSN32) && \
    103    !(defined __x86_64__ && defined __ILP32__)
    104 # define USE_LIBC_SYSCALL 1
    105 #endif
    106 
    107 #if defined USE_LIBC_SYSCALL
    108 	long res = syscall(__NR_times, &tbuf);
    109 
    110 	if (-1L == res)
    111 		return 77;
    112 	else
    113 		llres = (unsigned long) res;
    114 #elif defined __NR_times && defined __x86_64__ && defined __ILP32__
    115 	register long arg asm("rdi") = (long) &tbuf;
    116 	asm volatile("syscall\n\t"
    117 		     : "=a"(llres)
    118 		     : "0"(__NR_times), "r"(arg)
    119 		     : "memory", "cc", "r11", "cx");
    120 	if (llres > 0xfffffffffffff000)
    121 		return 77;
    122 #else
    123 	clock_t res = times(&tbuf);
    124 
    125 	if ((clock_t) -1 == res)
    126 		return 77;
    127 	if (sizeof(res) < sizeof(unsigned long long))
    128 		llres = (unsigned long) res;
    129 	else
    130 		llres = res;
    131 #endif
    132 
    133 	printf("times({tms_utime=%llu, tms_stime=%llu, ",
    134 		(unsigned long long) tbuf.tms_utime,
    135 		(unsigned long long) tbuf.tms_stime);
    136 	printf("tms_cutime=%llu, tms_cstime=%llu}) = %llu\n",
    137 		(unsigned long long) tbuf.tms_cutime,
    138 		(unsigned long long) tbuf.tms_cstime,
    139 		llres);
    140 	puts("+++ exited with 0 +++");
    141 
    142 	return 0;
    143 }
    144